POS1227 CAPISAS PROJECT: INCIDENCE AND EPIDEMIOLOGY OF ANTISINTETASE SYNDROME IN CATALONIA (SPAIN) BETWEEN 2016 AND 2019
Authors: M. Sallés Lizarzaburu, B. Busso, J. Narvaez, S. Holgado, A. Pros, E. Borrell, A. M. Millán Arciniegas, E. Ruiz, F. Morandeira, S. Mínguez, D. Taverner, D. A. Botello Corzo, J. A. Gómez-Puerta, I. Casafont-Solé, E. Riera Alonso, I. Carrión Barberà, D. Lobo Prat, S. Heredia, S. Ordoñez, M. Moreno Martinez-Losa, S. Rodriguez-Muguruza, C. García Gomez, M. Coll, V. Ortiz-Santamaria, M. Ricse Salcedo, T. Clavaguera Poch, E. Garcia Casares, N. Segales, E. Armengol, J. O. Codina Guino, R. Tourino, S. Garcia-Cirera, J. Camins, A. Arnau Bartes, E. Trallero Araguas
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Antisynthetase syndrome (ASSD) is an autoimmune disease characterized by the presence of antiaminoacyl tRNA-synthetase antibodies (ARS) and clinical manifestations that may include interstitial lung disease (ILD), myositis, arthritis, Raynaud´s phenomenon (RP), fever and mechanic's hands (MHs). The incidence rate is unknown and no population epidemiological studies have been published. <h3>Objectives</h3> To determine the incidence and epidemiology of ASSD between 2016 and 2019 in Catalonia. Diagnostic criteria considered were: the positivity of ARS associated with at least one major clinical manifestation (myositis, ILD or arthritis) <h3>Methods</h3> Restrospective multicentrical observational study. All patients with a first ARS (Jo1, PL7, PL12, OJ, EJ) positive during the period study were selected. Patient identifacation was carried out through the immunology laboratories of all the hospitals of the public catalan network. We estimed the cumulative incidence in the average population of Catalonia betwen 2016-2019 (7.526.982 individuals) and collected demographic, epidemiologic, clinical and immunologic data. <h3>Results</h3> We identified 201 patients with ARS, 125 of them met ASSD criteria. The estimated cumulative incidence was 1.66 cases per 100,000 inhabitants. Most were women (62.9%) with a mean age at diagnosis of 59.8 years (DE 15.4) and 78.3% southern european caucasians. Sixty three per cent worked in the tertiary sector and 20.5% in the secondary. Some environmental exposure were recognized in 17.9%, being contact with animals and asbestos the most common, and 38.8% were smokers or ex-smokers. Anti-Jo1 was the most frequent ARS (39.2%), followed by PL7 (28.8%), PL12 (21.6%), EJ (5.6%) and OJ(4.8%). ANA were positive in 74%, mostly with a cytoplasmic pattern (59,3%). Another specific ANA was present in 58.4%, predominantly Ro52 (48%). Rheumatoid factor, ACPA and ANCA were positive in 13.6%, 4.6% and 4.3% respectively. The mean age at first symptom was 58.5 years (DE 15.6). All patients presented at least one major manifestation: 45.6% one, 40.8% two and 13.6% three. ILD was present in 90.3%: subacute/chronic dyspnea 39.3%, cough 22.3%, rapidly progressive dyspnea 18.8% and 17% asymptomatic. HRCT patterns observed were: NSIP 50.5%, OP 15.3%, NSIP+OP 11,7%, UIP 11.7% and unclassifiable pattern 9.9%. Myositis was present in 64 cases (51.6%). Muscle biopsy was available in 34 cases: 50% dermatomyositis pattern, 36% polymiositis pattern, 20% indeterminate pattern and 1% necrotizing myositis. Arthritis was present in 27.2% (polyarthritis 78.6%, oligoarthritis 21.4%), RP 11.2%, fever 25.4% and skin manifestations 49,6% (71% MH's, 27.4% Gottron'n papules, 12.9% heliotrope rash and 3.2% shawl rash). First manifestation was ILD in 58.9% of patients, followed by myositis (21.4%) and arthritis (19.6%). Fifteen patients (12%) presented cancer, 8 of them less than 3 years from AS diagnosis. Breast cancer was the most common. In 14 cases (11.2%) another autoimmune disease was associated, highlighting 6 cases with Sjögren's syndrome. <h3>Conclusion</h3> The estimated cumulative incidence of ASSD between 2016 and 2019 in Catalonia was 1.66 cases per 100,000 inhabitants. Despite the absence of diagnostic criteria for ASSD, the presence of ARS is a necessary condition to establish it. We believe that identification of cases based on positive results of anti-ARS antibodies is a useful strategy to determine the incidence of ASSD in our territory. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.